fix(datadog): Add middleware for saving request metrics

middleware/metrics/__init__.py

@@ -0,0 +1,3 @@
+from metrics_middleware import DatadogMiddleware
+
+__all__ = [DatadogMiddleware]

middleware/metrics/metrics_middleware.py

@@ -0,0 +1,64 @@
+import time
+import traceback
+
+from django.conf import settings
+from django.utils.deprecation import MiddlewareMixin
+
+from datadog import initialize
+from datadog import statsd, api
+
+options = {
+    'api_key': settings.DATADOG_API_KEY,
+    'app_key': settings.DATADOG_APP_KEY
+}
+
+initialize(**options)
+
+
+class DatadogMiddleware(MiddlewareMixin):
+    """
+    Middleware to submit some metrics to DataDog about each requests.
+    """
+    DATADOG_TIMING_ATTRIBUTE = '_datadog_start_time'
+    app_name = settings.DATADOG_APP_NAME
+
+    def process_request(self, request):
+        setattr(request, self.DATADOG_TIMING_ATTRIBUTE, time.time())
+
+    def process_response(self, request, response):
+        if not hasattr(request, self.DATADOG_TIMING_ATTRIBUTE):
+            return response
+
+        request_time = time.time() - getattr(request, self.DATADOG_TIMING_ATTRIBUTE)
+
+        timing_metric = '{0}.request_time'.format(self.app_name)
+        count_metric = '{0}.no_of_requests_metric'.format(self.app_name)
+        success_metric = '{0}.no_of_successful_requests_metric'.format(self.app_name)
+        unsuccess_metric = '{0}.no_of_unsuccessful_requests_metric'.format(self.app_name)
+
+        tags = self._get_metric_tags(request)
+
+        if 200 <= response.status_code < 400:
+            statsd.increment(success_metric, tags=tags)
+        else:
+            statsd.increment(unsuccess_metric, tags=tags)
+
+        statsd.increment(count_metric, tags=tags)
+        statsd.histogram(timing_metric, request_time, tags=tags)
+
+        return response
+
+    def process_exception(self, request, exception):
+        exc = traceback.format_exc()
+        title = 'Exception from {0}'.format(request.path)
+        text = "Traceback: {0}".format(exc)
+
+        tags = self._get_metric_tags(request)
+        event_tags = [self.app_name, 'unhandled_exception']
+        app_error_metric = '{0}.unhandled_errors.{1}'.format(self.app_name, request.path)
+
+        statsd.increment(app_error_metric, tags=tags)
+        api.Event.create(title=title, text=text, tags=event_tags)
+
+    def _get_metric_tags(self, request):
+            return ['path:{0}'.format(request.path)]